Sample separating apparatus and method, and substrate manufacturing method

ABSTRACT

This invention is to provide an apparatus for separating a substrate having a porous layer at the porous layer. A bonded substrate stack ( 101 ) having a porous layer ( 10   b ) is supported by substrate holding portions ( 120, 150 ) while being rotated. High-speed, high-pressure water (jet) is ejected from a nozzle ( 102 ), so the jet is injected into the bonded substrate stack ( 101 ). The substrate holding portions ( 120, 150 ) hold the bonded substrate stack ( 101 ) such that the bonded substrate stack ( 101 ) can expand at its central portion due to the pressure of the injected water. This efficiently applies a force (separation force) that acts outward from the inside of the bonded substrate stack ( 101 ).

This application is a divisional of U.S. Ser. No. 09/211,757 filed Dec.15, 1998, now U.S. Pat. No. 6,418,999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a sample separating apparatus andmethod, and a substrate manufacturing method and, for example, to anapparatus and method of separating a plate-like sample having aninternal fragile layer at the fragile layer, a sample support apparatusused in the separating apparatus, and a substrate manufacturing methodusing the separating apparatus.

2. Description of the Related Art

A substrate (SOI substrate) having an SOI (Silicon On Insulator)structure is known as a substrate having a single-crystal Si layer on aninsulating layer. A device using this SOI substrate has many advantagesthat cannot be achieved by ordinary Si substrates. Examples of theadvantages are as follows.

(1) The integration degree can be increased because dielectric isolationis easy.

(2) The radiation resistance can be increased.

(3) The operating speed of the device can be increased because the straycapacitance is small.

(4) No well step is necessary.

(5) Latch-up can be prevented.

(6) A completely depleted field-effect transistor can be formed by thinfilm formation.

Since an SOI structure has the above various advantages, researches havebeen made on its formation method for several decades.

As one SOI technology, an SOS (Silicon On Sapphire) technology by whichSi is heteroepitaxially grown on a single-crystal sapphire substrate byCVD (Chemical Vapor Deposition) has been known for a long time. This SOStechnology was once recognized as the most matured SOI technology.However, the SOS technology has not been put into practical use to datebecause, e.g., a large amount of crystal defects are produced by latticemismatch in the interface between the Si layer and the underlyingsapphire substrate, aluminum that forms the sapphire substrate mixes inthe Si layer, the substrate is expensive, and it is difficult to obtaina large area.

Various SOI technology appeared following the SOS technology. For theseSOI technologies, various methods have been examined aiming at reducingcrystal defects or manufacturing cost. There are a method of implantingoxygen ions into a substrate to form a buried oxide layer, a method ofbonding two wafers via an oxide film and polishing or etching one of thewafers to leave a thin single-crystal Si layer on the oxide film, and amethod of implanting hydrogen ions to a predetermined depth from thesurface of an Si substrate having an oxide film, bonding the Sisubstrate to the other substrate, and peeling the latter substrate (theother substrate) by a heat treatment while leaving a thin single-crystalSi layer on the oxide film.

The present applicant has disclosed a new SOI technology in JapanesePatent Laid-Open No. 5-21338. In this technology, a first substrateobtained by forming a non-porous single-crystal layer (including asingle-crystal Si layer) on a single-crystal semiconductor substratehaving a porous layer is bonded to a second substrate via an insulatinglayer (SiO₂), and the two substrates are separated from the porous layerto transfer the non-porous single-crystal layer to the second substrate.This technology is advantageous in that the SOI layer has high filmthickness uniformity, the crystal defect density in the SOI layer can bedecreased, the SOI layer has high surface planarity, no expensivespecial fabrication apparatus is necessary, and SOI substrates havingSOI films about a few hundred ^(˜) to 10 μm thick can be fabricated bythe same fabrication apparatus.

In addition, the present applicant has disclosed another technology inJapanese Patent Laid-Open No. 7-302889 in which, after the first andsecond substrates described above are bonded, the first substrate isseparated from the second substrate without breaking, and the separatedfirst substrate is reused by smoothening the surface and again forming aporous layer. Since the first substrate can be economically used, thistechnology has the advantages that the fabrication cost can be largelyreduced and the fabrication process is also simple.

In the above technologies, however, when the two bonded substrates areseparated it is necessary to prevent damages to the substrates andprotect the fabrication apparatus and the like from contamination causedby the generation of particles.

SUMMARY OF THE INVENTION

The present invention has been made in consideration of the abovesituation, and has as its object to provide a separating apparatus andmethod suitable to separate a sample such as a substrate, a samplesupport apparatus used in this separating apparatus, and a substratemanufacturing method using the separating apparatus.

According to the present invention, there is provided a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a jet unit forejecting a fluid to the sample, and a pair of holding portions opposingeach other to sandwich and hold the sample, wherein the pair of holdingportions hold the sample to allow the sample to expand at a vicinity ofa central portion due to a pressure of the fluid ejected from the jetunit and injected into the sample.

According to the present invention, there is also provided a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a jet unit forejecting a fluid to the sample, and a pair of holding portions opposingeach other to sandwich and hold the sample, wherein the pair of holdingportions hold the sample which can corrugate due to a pressure of thefluid ejected from the jet unit and injected into the sample.

In the separating apparatus, preferably, at least one of the pair ofholding portions has a hollow contact portion, and the sample is held bybringing the contact portion into contact with the sample. The contactportion may comprise a multiple of contact portions.

In the separating apparatus, preferably, at least one of the pair ofholding portions has an annular contact portion, and the sample is heldby bringing the contact portion into contact with the sample. Thecontact portion may comprise a multiple of contact portions.

In the separating apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of stripe-shaped contactportions, and the sample is held by bringing the contact portion intocontact with the sample.

In the separating apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of arcuated contact portions,and the sample is held by bringing the contact portion into contact withthe sample.

In the separating apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of projecting contact portionson a main body surface, and the sample is held by bringing the contactportion into contact with the sample.

In the separating apparatus, preferably, at least one of the pair ofholding portions has a radial contact portion, and the sample is held bybringing the contact portion into contact with the sample.

In the separating apparatus, preferably, at least one of the pair ofholding portions has a contact portion which comes into contact with aperipheral portion of the sample, and the sample is held by bringing thecontact portion into contact with the sample. Preferably, the contactportion can contact the whole peripheral portion of the sample.

The separating apparatus preferably further comprises a rotary mechanismfor rotating the holding portion about a shaft perpendicular to asurface of the sample.

The separating apparatus preferably further comprises an adjustmentmechanism for adjusting an interval between the pair of holdingportions.

In the separating apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism presses the sample to adjust theinterval between the pair of holding portions.

In the separating apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism maintains a substantially constantinterval between the pair of holding portions.

In the separating apparatus, preferably, each of the pair of holdingportions has a chuck mechanism for vacuum-chucking the sample.

The separating apparatus is suitable for processing of separating asubstrate having a porous layer as the fragile layer.

According to the present invention, there is also provided a supportapparatus for supporting a sample, which is used in a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a pair ofholding portions opposing each other to sandwich and hold the sample,wherein the pair of holding portions hold the sample to allow the sampleto expand at a vicinity of a central portion due to a pressure of afluid ejected from a jet unit arranged in the separating apparatus andinjected into the sample.

According to the present invention, there is also provided a supportapparatus for supporting a sample, which is used in a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a pair ofholding portions opposing each other to sandwich and hold the sample,wherein the pair of holding portions hold the sample to allow the sampleto corrugate due to a pressure of a fluid ejected from a jet unitarranged in the separating apparatus and injected into the sample.

In the support apparatus, preferably, at least one of the pair ofholding portions has a hollow contact portion, and the sample is held bybringing the contact portion into contact with the sample. The contactportion may comprise a multiple of contact portions.

In the support apparatus, preferably, at least one of the pair ofholding portions has an annular contact portion, and the sample is heldby bringing the contact portion into contact with the sample. Thecontact portion may comprise a multiple of contact portions.

In the support apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of stripe-shaped contactportions, and the sample is held by bringing the contact portion intocontact with the sample.

In the support apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of arcuated contact portions,and the sample is held by bringing the contact portion into contact withthe sample.

In the support apparatus, preferably, at least one of the pair ofholding portions has one or a plurality of projecting contact portionson a main body surface, and the sample is held by bringing the contactportion into contact with the sample.

In the support apparatus, preferably, at least one of the pair ofholding portions has a radial contact portion, and the sample is held bybringing the contact portion into contact with the sample.

In the support apparatus, preferably, at least one of the pair ofholding portions has a contact portion which comes into contact with aperipheral portion of the sample, and the sample is held by bringing thecontact portion into contact with the sample. Preferably, the contactportion can contact the whole peripheral portion of the sample.

The support apparatus preferably further comprises a rotary mechanismfor rotating the holding portion about a shaft perpendicular to asurface of the sample.

The support apparatus preferably further comprises an adjustmentmechanism for adjusting an interval between the pair of holdingportions.

In the support apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism presses the sample to adjust theinterval between the pair of holding portions.

In the support apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism maintains a substantially constantinterval between the pair of holding portions.

In the support apparatus, preferably, each of the pair of holdingportions has a chuck mechanism for vacuum-chucking the sample.

The support apparatus is suitable as a support apparatus for supportinga substrate having a porous layer as the fragile layer during separationprocessing.

According to the present invention, there is also provided a sampleseparating method characterized by comprising separating a sample havinga fragile layer using the above separating apparatus.

In the separating method, preferably, water is used as the fluid to beejected from the jet unit.

According to the present invention, there is also provided a separatingmethod of separating a substrate at a porous layer, the substrate beingformed by bonding a non-porous layer side of a first substrate, in whichthe porous layer and the non-porous layer are sequentially formed on onesurface, to a second substrate, characterized in that the aboveseparating apparatus is used for separation.

According to the present invention, there is also provided a substratemanufacturing method characterized by comprising the step of bonding anon-porous layer side of a first substrate, in which a porous layer andthe non-porous layer are sequentially formed on one surface, to a secondsubstrate, and separating the bonded substrates at the porous layer,wherein the above separating apparatus is used in the separation step.

According to the present invention, there is also provided a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a jet unit forejecting a fluid to the sample, and a pair of holding portions opposingeach other to sandwich and hold the sample, wherein the pair of holdingportions allow the sample to warp as the sample is divided into twoparts by a pressure of the fluid ejected from the jet unit and injectedinto the sample and simultaneously limit a warp amount.

In the separating apparatus, preferably, at least one of the pair ofholding portions has a smooth convex support surface, and the sample isheld by the support surface.

In the separating apparatus, the support surface preferablysubstantially comprises part of a spherical surface.

In the separating apparatus, the support surface preferably comprises asurface formed by a cone with a convex vertex.

In the separating apparatus, the support surface preferablysubstantially comprises a surface formed by a frustum of a cone.

In the separating apparatus, the support surface preferably comprises asmooth convex surface formed by a stack of several frustums.

In the separating apparatus, the support surface preferably comprises aconvex surface formed by a stack of several columns.

In the separating apparatus, at least one of the pair of holdingportions preferably includes an elastic member and deforms due to aforce inflicted by the sample.

In the separating apparatus, preferably, at least one of the holdingportions has a support portion partially consisting of an elasticmaterial, and the sample is held by the support portion.

In the separating apparatus, at least one of the holding portionspreferably has an elastic member at a portion which can contact thesample.

In the separating apparatus, at least one of the holding portionspreferably has an annular support portion consisting of an elasticmember.

In the separating apparatus, at least one of the holding portionspreferably has a support portion coupled to a main body via an elasticmember.

The separating apparatus preferably further comprises a rotary mechanismfor rotating the holding portion about a shaft perpendicular to asurface of the sample.

The separating apparatus preferably further comprises an adjustmentmechanism for adjusting an interval between the pair of holdingportions.

In the separating apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism presses the sample to adjust theinterval between the pair of holding portions.

In the separating apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism maintains a substantially constantinterval between the pair of holding portions.

In the separating apparatus, each of the pair of holding portionspreferably has a chuck mechanism for vacuum-chucking the sample.

The separating apparatus is suitable for processing of separating asubstrate having a porous layer as the fragile layer.

According to the present invention, there is also provided a supportapparatus for supporting a sample, which is used in a separatingapparatus for separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising a pair ofholding portions for sandwiching and holding the sample, wherein thepair of holding portions allow the sample to warp as the sample isdivided into two parts by a pressure of the fluid ejected from a jetunit arranged in the separating apparatus and injected into the sampleand simultaneously limit a warp amount.

In the support apparatus, preferably, at least one of the pair ofholding portions has a smooth convex support surface, and the sample isheld by the support surface.

In the support apparatus, the support surface preferably substantiallycomprises part of a spherical surface.

In the support apparatus, the support surface preferably comprises asurface formed by a cone with a convex vertex.

In the support apparatus, the support surface preferably substantiallycomprises a surface formed by a frustum of a cone.

In the support apparatus, the support surface preferably comprises asmooth convex surface formed by a stack of several frustums.

In the support apparatus, the support surface preferably comprises aconvex surface formed by a stack of several columns.

In the support apparatus, at least one of the pair of holding portionspreferably includes an elastic member and deforms due to a forceinflicted by the sample.

In the support apparatus, preferably, at least one of the holdingportions has a support portion partially consisting of an elasticmaterial, and the sample is held by the support portion.

In the support apparatus, at least one of the holding portionspreferably has an elastic member at a portion which can contact thesample.

In the support apparatus, at least one of the holding portionspreferably has an annular support portion consisting of an elasticmember.

In the support apparatus, at least one of the holding portionspreferably has a support portion coupled to a main body via an elasticmember.

The support apparatus preferably further comprises a rotary mechanismfor rotating the holding portion about a shaft perpendicular to asurface of the sample.

The support apparatus preferably further comprises an adjustmentmechanism for adjusting an interval between the pair of holdingportions.

In the support apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism presses the sample to adjust theinterval between the pair of holding portions.

In the support apparatus, preferably, in separating the sample by thefluid, the adjustment mechanism maintains a substantially constantinterval between the pair of holding portions.

In the support apparatus, each of the pair of holding portionspreferably has a chuck mechanism for vacuum-chucking the sample.

The support apparatus is suitable as a support apparatus for supportinga substrate having a porous layer as the fragile layer during separationprocessing.

According to the present invention, there is also provided a sampleseparating method characterized by comprising separating a sample havinga fragile layer using the above separating apparatus.

In the separating method, water is preferably used as the fluid to beejected from the jet unit.

According to the present invention, there is also provided a separatingmethod of separating a substrate at a porous layer, the substrate beingformed by bonding a non-porous layer side of a first substrate, in whichthe porous layer and the non-porous layer are sequentially formed on onesurface, to a second substrate, characterized in that the aboveseparating apparatus is used for separation.

According to the present invention, there is also provided a substratemanufacturing method characterized by comprising the step of bonding anon-porous layer side of a first substrate, in which a porous layer andthe non-porous layer are sequentially formed on one surface, to a secondsubstrate, and separating the bonded substrates at the porous layer,wherein the above separating apparatus is used in the separation step.

The present invention has been made in consideration of the abovesituation, and has as its object to provide a separating apparatus andmethod suitable to separate a plate-like sample represented by asubstrate such as a bonded substrate stack, and a substratemanufacturing method to which the apparatus or method is applied.

According to the present invention, there is provided a separatingapparatus for separating a plate-like sample, characterized bycomprising a jet unit for ejecting a fluid for separating the sample tothe sample, and first and second holding portions for sandwiching andholding the sample, wherein the first and second holding portions haveholding surfaces with different shapes.

In the separating apparatus, preferably, the first holding portion holdsone surface of the sample to make a deflection amount of the one surfacedue to a pressure of the fluid injected into the sample relativelysmall, and the second holding portion holds the other surface of thesample to make a deflection amount of the other surface due to thepressure of the fluid relatively large.

In the separating apparatus, preferably, the first holding portion holdsone surface of the sample not to cause the one surface to deflect due toa pressure of the fluid injected into the sample, and the second holdingportion holds the other surface of the sample to cause the other surfaceto deflect due to the pressure of the fluid.

In the separating apparatus, the holding surface of the first holdingportion and the holding surface of the second holding portion preferablyhave different areas.

In the separating apparatus, preferably, the first holding portion has aholding surface for wholly holding one surface of the sample, and thesecond holding portion has a holding surface for partially holding theother surface of the sample.

In the separating apparatus, the holding surface of the first holdingportion preferably comprises a flat surface.

In the separating apparatus, the holding surface of the first holdingportion preferably comprises a curved surface.

In the separating apparatus, the holding surface of the second holdingportion is preferably annular.

In the separating apparatus, preferably, the second holding portion hasa plurality of projecting members, and the sample is held by tips of theplurality of projecting members.

In the separating apparatus, the second holding portion preferably has ashape allowing the sample to deflect while expanding at a centralportion on a side of the second holding portion due to the pressure ofthe fluid injected into the sample.

In the separating apparatus, the second holding portion preferably has ashape allowing the sample to deflect and corrugate on a side of thesecond holding portion due to the pressure of the fluid injected intothe sample.

The separating apparatus preferably further comprises a rotary mechanismfor rotating at least one of the first and second holding portions abouta shaft perpendicular to the holding surface to rotate the sample.

In the separating apparatus, preferably, the sample to be processedcomprises a substrate formed by bonding first and second substrates, andthe first and second substrates have different strengths.

According to the present invention, there is also provided a separatingmethod of separating a plate-like sample, characterized by comprisingholding the sample by sandwiching the sample by a pair of holdingportions having holding surfaces with different shapes, and ejecting afluid to a predetermined position in a direction of thickness of thesample, thereby separating the sample.

In the separating method, preferably, the sample to be separated has aninternal fragile layer, and in separating the sample, the fluid isejected to the fragile layer.

According to the present invention, there is also provided a separatingmethod of separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising the separationstep of ejecting a fluid to the fragile layer of the sample to separatethe sample, wherein in the separation step, one surface of the sample isheld to make a deflection amount due to a pressure of the fluid injectedinto the sample relatively small and the other surface of the sample isheld to make a deflection amount due to the pressure of the fluidinjected into the sample relatively large.

According to the present invention, there is also provided a separatingmethod of separating a plate-like sample having an internal fragilelayer at the fragile layer, characterized by comprising the separationstep of ejecting a fluid to the fragile layer of the sample to separatethe sample, wherein in the separation step, one surface of the sample isheld to limit deflection due to a pressure of the fluid injected intothe sample and the other surface of the sample is held to allowdeflection due to the pressure of the fluid injected into the sample.

The separating method preferably further comprises rotating the sampleabout a shaft perpendicular to a major surface of the sample inseparating the sample by the fluid.

In the separating method, preferably, the sample to be processedcomprises a sample formed by bonding first and second substrates, andthe first and second substrates have different strengths.

According to the present invention, there is also provided a separatingmethod of separating a composite substrate which has a fragile layerbetween a first substrate having a relatively low strength and a secondsubstrate having a relatively high strength, at the fragile layer,characterized by comprising the separation step of ejecting a fluid tothe fragile layer to separate the composite substrate, wherein in theseparation step, the first substrate is held to make a deflection amountdue to a pressure of the fluid injected into the composite substraterelatively small and the second substrate is held to make a deflectionamount due to the pressure of the fluid injected into the compositesubstrate relatively large.

According to the present invention, there is also provided a separatingmethod of separating a composite substrate which has a fragile layerbetween a first substrate having a relatively low strength and a secondsubstrate having a relatively high strength, at the fragile layer,characterized by comprising the separation step of ejecting a fluid tothe fragile layer to separate the composite substrate, wherein in theseparation step, the first substrate is held to limit deflection due toa pressure of the fluid injected into the composite substrate and thesecond substrate is held to allow deflection due to the pressure of thefluid injected into the composite substrate.

According to the present invention, there is also provided a substratemanufacturing method characterized by comprising the step of bonding anon-porous layer side of a first substrate, in which a porous layer andthe non-porous layer are sequentially formed on one surface, to a secondsubstrate, and separating the bonded substrates at the porous layer,wherein any one of the above separating apparatuses is used in theseparation step.

According to the present invention, there is also provided a substratemanufacturing method characterized by comprising bonding a non-porouslayer side of a first substrate, in which a porous layer and thenon-porous layer are sequentially formed on one surface, to a secondsubstrate, and separating the bonded substrates at the porous layer,wherein the separation step is executed using any one of the abovemethods.

According to the present invention, there is also provided a holdingapparatus for holding a sample in ejecting a fluid to a predeterminedposition in a direction of thickness of the sample to separate thesample, characterized in that the sample is held by a pair of holdingportions whose holding surfaces for holding the sample have differentshapes.

Further objects, features and advantages of the present invention willbecome apparent from the following detailed description of embodimentsof the present invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1E are views for explaining a method of manufacturing an SOIsubstrate according to the first embodiment of the present invention;

FIG. 2 is a view showing the schematic arrangement of a separatingapparatus according to the first embodiment of the present invention;

FIG. 3 is a perspective view of substrate holding portions according tothe first example of the first embodiment;

FIG. 4 is a front view of the substrate holding portion according to thefirst example of the first embodiment;

FIG. 5 is a sectional view of the substrate holding portions accordingto the first example of the first embodiment;

FIG. 6 is a view showing a modification of the substrate holding portionaccording to the first example of the first embodiment;

FIG. 7 is a view showing another modification of the substrate holdingportion according to the first example of the first embodiment;

FIG. 8 is a view showing still another modification of the substrateholding portion according to the first example of the first embodiment;

FIG. 9 is a view showing still another modification of the substrateholding portion according to the first example of the first embodiment;

FIG. 10 is a front view of a substrate holding portion according to thesecond example of the first embodiment;

FIG. 11 is a sectional view of the substrate holding portions accordingto the second example of the first embodiment;

FIG. 12 is a perspective view of substrate holding portions according tothe third example of the first embodiment;

FIG. 13 is a perspective view showing a modification of the substrateholding portions according to the third example of the first embodiment;

FIG. 14 is a perspective view of substrate holding portions according tothe fourth example of the first embodiment;

FIG. 15 is a perspective view showing a modification of the substrateholding portions according to the fourth example of the firstembodiment;

FIG. 16 is a perspective view of substrate holding portions according tothe fifth example of the first embodiment;

FIG. 17 is a front view of the substrate holding portion according tothe fifth example of the first embodiment;

FIG. 18 is a perspective view of substrate holding portions according tothe sixth example of the first embodiment;

FIG. 19 is a front view of the substrate holding portion according tothe sixth example of the first embodiment;

FIG. 20 is a perspective view showing a modification of the substrateholding portions according to the sixth example of the first embodiment;

FIG. 21 is a perspective view showing another modification of thesubstrate holding portions according to the sixth example of the firstembodiment;

FIG. 22 is a perspective view showing still another modification of thesubstrate holding portions according to the sixth example of the firstembodiment;

FIG. 23 is a perspective view showing still another modification of thesubstrate holding portions according to the sixth example of the firstembodiment;

FIG. 24 is a perspective view showing still another modification of thesubstrate holding portions according to the sixth example of the firstembodiment;

FIG. 25 is a sectional view of substrate holding portions according tothe seventh example of the first embodiment;

FIG. 26 is a sectional view of the substrate holding portions accordingto the seventh example of the first embodiment;

FIGS. 27A and 27B are views showing a force acting on a bonded substratestack in the presence and absence of a V-shaped groove;

FIG. 28 is a view showing the schematic arrangement of a separatingapparatus according to the second embodiment of the present invention;

FIG. 29 is a perspective view of substrate holding portions according tothe first example of the second embodiment;

FIG. 30 is a sectional view of the substrate holding portions accordingto the first example of the second embodiment;

FIG. 31 is a sectional view of the substrate holding portions accordingto the first example of the second embodiment;

FIG. 32 is a sectional view showing a modification of the substrateholding portions according to the first example of the secondembodiment;

FIG. 33 is a sectional view showing another modification of thesubstrate holding portions according to the first example of the secondembodiment;

FIG. 34 is a sectional view showing still another modification of thesubstrate holding portions according to the first example of the secondembodiment;

FIG. 35 is a sectional view showing still another modification of thesubstrate holding portions according to the first example of the secondembodiment;

FIG. 36 is a sectional view showing a modification of substrate holdingportions according to the second example of the second embodiment;

FIG. 37 is a sectional view showing another modification of thesubstrate holding portions according to the second example of the secondembodiment;

FIG. 38 is a sectional view showing still another modification of thesubstrate holding portions according to the second example of the secondembodiment;

FIG. 39 is a sectional view showing still another modification of thesubstrate holding portions according to the second example of the secondembodiment;

FIG. 40 is a sectional view showing still another modification of thesubstrate holding portions according to the second example of the secondembodiment;

FIGS. 41A to 41E are views showing for explaining another method ofmanufacturing an SOI substrate according to the preferred embodiment ofthe present invention;

FIG. 42 is a view showing the schematic arrangement of a separatingapparatus according to the third embodiment of the present invention;

FIG. 43 is a perspective view of part of the separating apparatus shownin FIG. 42;

FIG. 44 is a view schematically showing separation processing;

FIG. 45 is a view showing the schematic arrangement of a separatingapparatus of the first modification;

FIG. 46 is a view showing the schematic arrangement of substrate holdingportions of a separating apparatus of the second modification;

FIG. 47 is a view showing the schematic arrangement of a substrateholding portion (on the first substrate side) of the third modification;and

FIG. 48 is a view showing the schematic arrangement of the othersubstrate holding portion (on the second substrate side) of the thirdmodification.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the present invention will be described belowwith reference to the accompanying drawings.

FIGS. 1A to 1E are views for explaining a method of manufacturing an SOIsubstrate according to a preferred embodiment of the present invention.

Referring to FIG. 1A, a single-crystal Si substrate 11 is prepared, anda porous Si layer 12 is formed on the surface of the single-crystal Sisubstrate 11 by anodizing. Referring to FIG. 1B, a non-poroussingle-crystal Si layer 13 is epitaxially grown on the porous Si layer12. With this process, a first substrate 10 is formed.

Referring to FIG. 1C, a second substrate 20 having an insulating layer(e.g., an SiO₂ layer) 15 formed on the surface of a single-crystal Sisubstrate 14 is prepared. The first substrate 10 and the secondsubstrate 20 are brought into contact with each other at roomtemperature such that the non-porous single-crystal Si layer 13 opposesthe insulating layer 15. After this, the first substrate 10 and thesecond substrate 20 are bonded by anode bonding, pressing, heating, or acombination thereof. With this process, the non-porous single-crystal Silayer 13 and the insulating layer 15 are firmly bonded. The insulatinglayer 15 may be formed on the single-crystal Si substrate 14 side, asdescribed above, on the non-porous single-crystal Si layer 13 as will bedescribed later, or on both the single-crystal Si substrate 14 and thenon-porous single-crustal Si layer 13 sides as far as the state shown inFIG. 1C is obtained by bringing the first and second substrates intocontact.

Referring to FIG. 1D, the two substrates bonded to each other areseparated at the porous Si layer 12. The second substrate side (10″+20)has a multilayered structure of a porous Si layer 12″, single-crystal Silayer 13, insulating layer 15, and single-crystal Si substrate 14. Onthe first substrate side (10′), a porous Si layer 12′ is formed on thesingle-crystal Si substrate 11.

After separation, the remaining porous Si layer 12′is removed from thesubstrate 101. The surface of the substrate 10′ is planarized, asneeded, so the substrate 10′ is used again as a single-crystal Sisubstrate 11 for forming a first substrate 10.

After the bonded substrate stack is separated, in FIG. 1E, the porouslayer 12″ on the second substrate side (10″+20) is selectively removedwith this process, a substrate having a multilayered structure of thesingle-crystal Si layer 13, insulating layer 15, and single-crystal Sisubstrate 14, i.e., an SOI structure is obtained.

FIGS. 41A to 41E are views for explaining another method ofmanufacturing an SOI substrate according to the preferred embodiment ofthe present invention.

Referring to FIG. 41A, a single-crystal Si substrate 11 is prepared, anda porous Si layer 12 is formed on the surface of the single-crystal Sisubstrate 11 by anodizing. Referring to FIG. 41B, a single-crystal Silayer 13 as a non-porous layer is epitaxially grown on the porous Silayer 12. After this, the surface of the single-crystal Si layer 13 isoxidized to form an SiO₂ layer 15. With this process, a first substrate10 is formed.

Referring to FIG. 41C, a single-crystal Si substrate 14 is prepared as asecond substrate 20. The first substrate 10 and the second substrate 20are brought into contact with each other at room temperature such thatthe SiO₂ layer 15 of the first substrate 10 opposes the second substrate20. The first substrate 10 and the second substrate 20 are bonded byanode bonding, pressing, heating, or a combination thereof. With thisprocess, the second substrate 20 and the SiO₂ layer 15 are firmlybonded. The SiO₂ layer 15 may be formed on the single-crystal Sisubstrate 11 side, on the second substrate 20, as described above, or onboth the single-crystal Si substrate 11 and the second substrate 20sides as far as the state shown in FIG. 41C is obtained by bringing thefirst and second substrates into contact.

Referring to FIG. 41D, the two substrates bonded to each other areseparated at the porous Si layer 12. The second substrate side has amultilayered structure of a porous Si layer 12″, single-crystal Si layer13, SiO₂ layer 15, and single-crystal Si substrate 14. On the firstsubstrate 10′ side, the porous Si layer 12′ is formed on thesingle-crystal.Si substrate 11.

After separation, the remaining porous Si layer 12′ is removed from thesubstrate 10′. The surface of the substrate 10′ is planarized, asneeded, so the substrate 10′ is used again as a single-crystal Sisubstrate 11 for forming a first substrate 10.

After the bonded substrate stack is separated, in FIG. 41E, the porouslayer 12″ on the second substrate side (10″+20) is selectively removed.With this process, a substrate having a multilayered structure of thesingle-crystal Si layer 13, insulating layer 15, and single-crystal Sisubstrate 14, i.e., an SOI structure is obtained.

As the second substrate, in addition to a single-crystal Si substrate,an insulating substrate (e.g., a substrate of silica glass) or atransparent substrate (e.g., a substrate of silica glass) can be used.

In this embodiment, to facilitate processing of bonding two substratesand separating them, a porous Si layer 12 having a fragile structure isformed in the separation region. In place of the porous layer, amicrocavity layer may be formed. A microcavity layer can be formed by,e.g., implanting ions into a semiconductor substrate.

The substrate manufactured by the above manufacturing method can beapplied not only to manufacture a semiconductor device but also tomanufacture a microstructure.

In this embodiment, in the step shown in FIG. 1D or 41D, i.e., in thestep of separating the two substrates bonded to each other (to bereferred to as a bonded substrate stack hereinafter), a separatingapparatus for selectively ejecting a high-pressure liquid or gas (fluid)to the porous Si layer as a separation region is used to separate thesubstrate stack into two substrates at the separation region.

First Embodiment

[Basic Arrangement of Separating Apparatus]

This separating apparatus uses the water jet method. Generally, thewater jet method ejects a high-speed, high-pressure stream of water(when a hard object is to be cut, an abrasive is added to water) upon anobject to, e.g., cut or process a ceramic, a metal, a concrete, a resin,a rubber, or a wood member, remove a coating film from the surface, orclean the surface (“Water Jet”, Vol. 1, No. 1, page 4, (1984)).Conventionally, the water jet method is used to perform theabove-described cutting, processing, remove a coating film, or clean thesurface mainly by partially removing the material.

This separating apparatus ejects a high-speed, high-pressure stream offluid to the porous layer (separation region) of the bonded substratestack as a fragile structure portion in the direction of substratesurface to selectively break the porous layer, thereby separating thesubstrate at the porous layer. The stream will be referred to as a “jet”hereinafter. The fluid forming a jet will be referred to as a “jetmedium”. As the jet medium, it is possible to use an organic solventsuch as water or alcohol, an acid such as fluoric acid or nitric acid,an alkali such as potassium hydroxide, a gas such as air, nitrogen gas,carbonic acid gas, rare gas, or an etching gas, or a plasma.

When this separating apparatus is to be applied to manufacture asemiconductor device, e.g., separate a bonded substrate stack, purewater with minimum impurity metals or particles is preferably used asthe jet medium. However, since separation processing is a perfectlow-temperature process, water with high purity need not always be usedas the jet medium, and the substrate may be cleaned after completion ofseparation processing.

In this separating apparatus, a jet is ejected to the porous layer(separation region) exposed to the side surface of the bonded substratestack, thereby removing the porous layer from the peripheral portion tothe central portion. With this process, the bonded substrate stack isseparated into two substrates by removing only the separation regionwith low mechanical strength without damaging the main body. Even whenthe side surface of the bonded substrate stack is covered with some thinlayer, and the porous layer is not exposed, the thin layer can beremoved by the jet, so the bonded substrate stack can be separated bythe above-described method.

To separate the bonded substrate stack only by the cutting force of jet,a high pressure of several thousand kgf/cm² or more must be applied tothe jet medium. In this case, the outer peripheral portion of the bondedsubstrate stack may be damaged, or the internal pressure of theseparation region may increase to break the bonded substrate stack.

To avoid this situation, the pressure to be applied to the jet medium ispreferably set to be as low as about 500 kgf/cm² When such alow-pressure jet is employed, the bonded substrate stack is separated byinjecting the jet medium into the bonded substrate stack to expand andsplit it into two substrates rather than by colliding the jet againstthe porous layer to cut the porous layer by impact. Therefore, offcut israrely produced, and damages to substrates decrease. In addition, thejet medium need contain no abrasive.

At the peripheral portion of the bonded substrate stack, the effect forsplitting the bonded substrate stack into two substrates effectivelyacts when a V-shaped (concave) groove is formed in the bonded substratestack along the side surface. FIGS. 27A and 27B are views showing aforce acting on the bonded substrate stack in the presence and absenceof a V-shaped groove. FIG. 27A shows a bonded substrate stack having aV-shaped groove 22. FIG. 27B shows a bonded substrate stack having noV-shaped groove.

As shown in FIG. 27A, in the bonded substrate stack having the V-shapedgroove 22, a force (to be referred to as a separation force hereinafter)is applied outward from the center of the bonded substrate stack, asindicated by an arrow 23. On the other hand, as shown in FIG. 27B, inthe bonded substrate stack with a convex side surface, a force isapplied inward from the side surface of the bonded substrate stack, asindicated by an arrow 24. In the bonded substrate stack having a convexside surface, the separation force does not act unless the side surfaceof the porous layer 12 as the separation region is removed by a jet 21.

Even when a thin film is formed on the side surface of the bondedsubstrate stack, the separation force acts on the bonded substrate stackas far as the bonded substrate stack has the V-shaped groove 22, asshown in FIG. 27A, so the thin layer can be easily broken.

To prevent damages to the substrates, the separation force in the axialdirection of the bonded substrate stack is preferably set to be severalhundred gf/cm².

To effectively use the jet, a width W1 of the V-shaped groove 22 ispreferably equal to or larger than a diameter d of the jet 21. Forexample, assume that each of the first substrate (10) and the secondsubstrate (20) has a thickness of about 1 mm, and the bonded substratestack has a thickness of about 2 mm. Since the width W1 of the V-shapedgroove 22 is normally around 1 mm, the diameter of the jet is preferably1 mm or less. Since a general water jet apparatus uses a jet with adiameter of approximately 0.1 to 0.5 mm, such a general water jetapparatus (e.g., a water jet nozzle) can be used.

The nozzle for ejecting a jet can have not only a circular shape but anyother shapes. For example, when a slit-like nozzle is employed to ejecta jet having a long rectangular section, the jet can be efficientlyinjected into the separation region (inserted between the twosubstrates).

The jet ejection conditions are determined in accordance with the typeof separation region (e.g., a porous layer) or the shape of the sidesurface of the bonded substrate stack. Important parameters as the jetejection conditions are the pressure applied to the jet medium, the jetscanning speed, the width or diameter of the nozzle (the nozzle diameteris almost the same as the jet diameter), the nozzle shape, the distancebetween the nozzle and the separation region, and the flow rate of thejet medium.

The following techniques are used to separate the bonded substratestack. 1) The jet is injected into the bonding interface parallel to thebonding interface while the nozzle is scanned along the bondinginterface. 2) The jet is injected into the bonding interface parallel tothe bonding interface while the bonded substrate stack is scanned. 3)The jet is injected into the bonding interface parallel to the bondinginterface and simultaneously scanned in a fan shape at a pivot near thenozzle. 4) The jet is injected into the bonding interface parallel tothe bonding interface while the bonded substrate stack is rotated aboutnearly the center of the bonded substrate stack (this technique isparticularly effective when the bonded substrate stack has a diskshape). The jet need not always be ejected to be perfectly parallel tothe bonding interface.

FIG. 2 is a view showing the schematic arrangement of a separatingapparatus according to the first embodiment of the present invention. Toseparate a bonded substrate stack by a low-pressure jet, a separatingapparatus 100 supports the bonded substrate stack such that theseparation force efficiently acts on the bonded substrate stack. As aspecific example, the separating apparatus 100 supports a bondedsubstrate stack such that the bonded substrate stack can expand at itscentral portion by the pressure of the jet medium injected into thebonded substrate stack. As another example, the separating apparatus 100supports a bonded substrate stack such that the bonded substrate stackcan corrugate by the pressure of the jet medium injected into the bondedsubstrate stack.

The separating apparatus 100 has substrate holding portions 120 and 150having vacuum chuck mechanisms. A bonded substrate stack 101 issandwiched by the substrate holding portions 120 and 150 and held. Thebonded substrate stack 101 has a porous layer 101 b as an internalfragile structure and is separated into two substrates 101 a and 101 cat the porous layer 101 b by the separating apparatus 100. In thisseparating apparatus 100, the bonded substrate stack is set such thatthe substrate 101 a is placed on the first substrate (10′) side in FIG.1D or 41D and the substrate 101 c is placed on the second substrate(10″+20) side in FIG. 1D or 41D.

The substrate holding portions 120 and 150 are present on the samerotary axis. The substrate holding portion 120 is coupled to one end ofa rotary shaft 104 which is rotatably axially supported by a supportbase 109 through a bearing 108. The other end of the rotary shaft 104 iscoupled to the rotary shaft of a motor 110. The rotational forcegenerated by the motor 110 rotates the bonded substrate stack 101vacuum-chucked by the substrate holding portion 120. In separating thebonded substrate stack 101, the motor 110 rotates the rotary shaft 104at a designated rotation speed in accordance with an instruction from acontroller (not shown).

The substrate holding portion 150 is coupled to one end of a rotaryshaft 103 which is rotatably and slidably axially supported by thesupport base 109 through a bearing 111. The other end of the rotaryshaft 103 is coupled to an air cylinder 112 fixed on the support base109. When the air cylinder 112 pushes the rotary shaft 103, the bondedsubstrate stack 101 is pressed by the substrate holding portion 150.

The substrate holding portions 120 and 150 can be detached from therotary shafts 104 and 103, respectively. The substrate holding portions120 and 150 have one or a plurality of suction holes 181 and 182 asvacuum chuck mechanism, respectively. The suction holes 181 and 182communicate with rotary seal portions 104 a and 103 a through the rotaryshafts 104 and 103, respectively. The rotary seal portions 104 a and 103a are coupled to vacuum lines 104 b and 103 b, respectively. Thesevacuum lines 104 b and 103 b have solenoid valves. By controlling thesolenoid valves, setting/removal of the bonded substrate stack 101 canbe controlled.

The substrate holding portions 120 and 150 hold the bonded substratestack 101 such that the separation force efficiently acts on the bondedsubstrate stack 101 in separation processing. Specific arrangements ofthe substrate holding portions 120 and 150 will be described later.

Substrate separation processing using this separating apparatus 100 willbe described below.

To set the bonded substrate stack 101 in the separating apparatus 100,first, the rotary shaft 103 is retracted by the air cylinder 112 to seta predetermined interval between the chucking surfaces of the substrateholding portions 120 and 150. After the bonded substrate stack 101 ismounted on an alignment shaft 113, the air cylinder 112 pushes therotary shaft 103, so the bonded substrate stack 101 is pressed and held(the state shown in FIG. 2). The alignment shaft 113 is rotatablyaxially supported by the support base 109 through bearings 105 and 107.

In this embodiment, the bonded substrate stack 101 is held not by vacuumchucking but by the pressing force of the air cylinder 112. The pressingforce is preferably about 100 to 2000 gf. The bonded substrate stack 101may be vacuum-chucked, as a matter of course. In separation processing,the air cylinder 112 is preferably controlled to maintain apredetermined interval between the substrate holding portions 120 and150.

A jet medium (e.g., water) is sent from a pump 114 to a nozzle 102, andprocessing waits until the jet ejected from the nozzle 102 stabilizes.When the jet stabilizes, a shutter 106 is opened to inject the jet intothe separation region of the bonded substrate stack 101. At this time,the bonded substrate stack 101 is rotated by the motor 110. The rotaryshaft 104, substrate holding portion 120, bonded substrate stack 101,substrate holding portion 150, and rotary shaft 103 integrally rotate.

When the jet is injected, a separation force due to the pressure of thejet medium continuously injected into the porous layer 101 b as afragile structure acts on the bonded substrate stack 101 to break theporous layer 101 b which connects the substrates 101 a and 101 c. Withthis processing, the bonded substrate stack 101 is separated into twosubstrates in about 2 min.

When the bonded substrate stack 101 is separated into two substrates,the shutter 106 is closed, and the operation of pump 114 is stopped. Bystopping rotation of the motor 110 and controlling the above-describedelectromagnetic valves, the separated substrates are vacuum-chucked bythe substrate holding portions 120 and 150.

When the air cylinder 112 retracts the rotary shaft 103, the surfacetension of the jet medium (e.g., water) is cut off to split the twophysically separated substrates to both sides.

When the separation force is to efficiently act on the bonded substratestack 101, the structure of the substrate holding portions 120 and 150must be optimized. In this embodiment, the separation force isefficiently used by ensuring a space in which the bonded substrate stackdeflects in separation processing. Preferable arrangements of substrateholding portions will be listed below. In the following examples, thesubstrate holding portions 120 and 150 have a symmetrical structure.However, the substrate holding portions 120 and 150 may have independentstructures.

[First Example of Substrate Holding Portion]

FIGS. 3 to 5 are views showing the arrangement of substrate holdingportions according to the first example of the present invention. FIG. 3is a perspective view, FIG. 4 is a front view, and FIG. 5 is a sectionalview. Substrate holding portions 121 and 151 shown in FIGS. 3 to 5 areexamples of the substrate holding portions 120 and 150 shown in FIG. 2,respectively.

The substrate holding portions 121 and 151 of the first example haveannular contact portions 121 a and 151 a which come into contact withthe bonded substrate stack 101. With this structure, the bondedsubstrate stack 101 can deflect having “nodes” at a portion sandwichedby the contact portions 121 a and 151 a and “antinodes” near the centraland peripheral portions of the bonded substrate stack 101. In otherwords, the substrate holding portions 121 and 151 have a structure inwhich the central portion of the bonded substrate stack 101 can expandin separation processing or a structure in which the bonded substratestack 101 can corrugate in separation processing. When the substrateholding portions 121 and 151 having this structure are employed, theseparation force can efficiently act inside the bonded substrate stack101.

With the use of the substrate holding portions 121 and 151, separationprogresses from the side surface portion of the bonded substrate stack101 to the vicinity of the contact portions 121 a and 115 a in about 30sec after the start of jet injection into the bonded substrate stack 101(separation processing). In about 2 min after the start of separationprocessing, the bonded substrate stack 101 warps outward at its centralportion to form “antinodes” and is completely separated.

The outer diameter of each of the contact portions 121 a and 151 a ispreferably, e.g., 30 to 50 mm. The inner diameter of each of the contactportions 121 a and 151 a can be smaller than the outer diameter by,e.g., approximately 10 mm. However, for easy deflection of the substratestack to be separated, the inner diameter of each of the contactportions 121 a and 151 a is preferably close to the outer diameter.

Any other substrate holding portion can provide the same effect asdescribed above as far as it allows the bonded substrate stack 101 todeflect forming “nodes” and “antinodes”. FIGS. 6 to 9 are front viewsshowing modifications of the substrate holding portion according to thefirst example. Reference numerals 122 a, 152 a, 123 a, 153 a, 124 a, 154a, 125 a, and 155 a denote contact portions at which the substrateholding portions are in contact with the bonded substrate stack 101.FIGS. 6 to 8 show examples of a contact portion having a polygonal shapewith a hollow center. FIG. 9 shows an example of contact portion whosecenter is shifted from the center of the bonded substrate stack 101.These are examples of a stripe-shaped contact portion.

[Second Example of Substrate Holding Portion]

FIGS. 10 and 11 are views showing the arrangement of substrate holdingportions according to the second example of the present invention. FIG.10 is a front view, and FIG. 11 is a sectional view. Substrate holdingportions 126 and 156 shown in FIGS. 10 and 11 are examples of thesubstrate holding portions 120 and 150 shown in FIG. 2, respectively.

The substrate holding portion 126 of this example has two annularcontact portions 126 a and 126 b which come into contact with the bondedsubstrate stack 101. The substrate holding portion 156 has two annularcontact portions 156 a and 156 b which come into contact with the bondedsubstrate stack 101. The substrate holding portions 126 and 156 of thisexample are particularly suitable to process a substrate stack with alarge size (e.g., 8 inches or more).

With these substrate holding portions 126 and 156, the bonded substratestack 101 can deflect having “nodes” at a circumferential portionsandwiched by the contact portions 126 a and 156 a and a portionsandwiched by the contact portions 126 b and 156 b, and “antinodes” nearthe intermediate portion between the contact portions and the peripheralportion of the bonded substrate stack 101.

When the substrate holding portions 126 and 156 having a structure inwhich the bonded substrate stack 101 deflects while corrugating orexpanding near the central portion are employed, the separation forcecan efficiently act inside the bonded substrate stack 101.

With the use of the substrate holding portions 126 and 156, separationprogresses from the side surface of the bonded substrate stack 101 tothe vicinity of the outer contact portions 126 a and 156 a in about 30sec after the start of jet injection into the bonded substrate stack 101(separation processing). In about 30 sec after this, the bondedsubstrate stack 101 is separated to the outer contact portions 126 b and156 b. In about 3 min after the start of separation processing, thebonded substrate stack 101 warps to form “nodes” and “antinodes” and iscompletely separated.

The widths of the contact portions (diameter difference) can bearbitrarily determined. However, for easy deflection of the substratestack to be separated, the width of each contact portion is preferablysmall.

In this example, two sets of contact portions are formed. However, threeor more sets of contact portions may be arranged.

[Third Example of Substrate Holding Portion]

FIG. 12 is a perspective view showing the arrangement of substrateholding portions according to the third example of the presentinvention. Substrate holding portions 127 and 157 shown in FIG. 12 areexamples of the substrate holding portions 120 and 150 shown in FIG. 2,respectively.

The substrate holding portions 127 and 157 of this example have aplurality of contact portions 127 a and 157 a which come into contactwith the bonded substrate stack 101, respectively. Stated differently,this structure has annular contact portions 121 a and 151 a of the firstexample with grooves 127 b and 157 b which divide the contact portions121 a and 151 a, respectively.

The grooves 127 b and 157 b prevent the separation force fromexcessively acting in the vicinity of the central portion of the bondedsubstrate stack 101. More specifically, when the grooves 127 b and 157 bare formed, the jet medium injected into the central portion of thebonded substrate stack 101 can be appropriately discharged, so the jetmedium pressure can be prevented from excessively increasing near thevicinity of the central portion. Therefore, the bonded substrate stack101 can be prevented from breaking because of a portion of the porouslayer, where the mechanical strength is locally high and separationprogresses slowly.

With the use of the substrate holding portions 127 and 157, separationprogresses from the side surface of the bonded substrate stack 101 tothe vicinity of the contact portions 127 a and 157 a in about 30 secafter the start of jet injection into the bonded substrate stack 101(separation processing). In about 2 min after the start of separationprocessing, the bonded substrate stack 101 warps outward at its centralportion to form “antinodes” and is completely separated.

FIG. 13 is a perspective view showing a modification of the substrateholding portions shown in FIG. 12. Substrate holding portions 128 and158 shown in FIG. 13 are examples of the substrate holding portions 120and 150 shown in FIG. 2, respectively.

The substrate holding portion 128 of this modification has a pluralityof columnar contact portions 128 a forming a circle on a main body 128b. The substrate holding portion 158 has the same arrangement as that ofthe substrate holding portion 128. With the substrate holding portions128 and 158 as well, the jet medium pressure can be prevented fromexcessively increasing inside the bonded substrate stack 101, so thebonded substrate stack 101 can be prevented from breaking.

[Fourth Example of Substrate Holding Portion]

FIG. 14 is a perspective view showing the arrangement of substrateholding portions according to the fourth example of the presentinvention. Substrate holding portions 129 and 159 shown in FIG. 14 areexamples of the substrate holding portions 120 and 150 shown in FIG. 2,respectively.

The substrate holding portion 129 of this example has two types ofarcuated contact portions 129 a and 129 c which come into contact withthe bonded substrate stack 101. To put it differently, the structure hasthe annular contact portions 126 a and 126 b of the second example withgrooves 128 b and 128 d which divide the contact portions 126 a and 126b, respectively. The substrate holding portion 159 has the samearrangement as that of the substrate holding portion 129.

With the use of the substrate holding portions 129 and 159, separationprogresses from the side surface of the bonded substrate stack 101 tothe vicinity of the outer contact portion 129 a in about 30 sec afterthe start of jet injection into the bonded substrate stack 101(separation processing). In about 30 sec after this, the bondedsubstrate stack 101 is separated to the vicinity of the inner contactportion 129 c. In about 3 min after the start of separation processing,the bonded substrate stack 101 is completely separated while corrugatingto form “nodes” and “antinodes”.

By forming grooves 129 b and 129d in the arcuated contact portions 129 aand 129 c, respectively (this also applies to the substrate holdingportion 159), the jet medium pressure can be prevented from excessivelyincreasing inside the bonded substrate stack 101. Hence, the bondedsubstrate stack 101 can be prevented from breaking because of a portionof the porous layer, where the mechanical strength is locally high andseparation progresses slowly.

FIG. 15 is a perspective view showing a modification of the substrateholding portions shown in FIG. 14. Substrate holding portions 130 and160 shown in FIG. 15 are examples of the substrate holding portions 120and 150 shown in FIG. 2, respectively.

The substrate holding portion 130 of this modification has a pluralityof columnar contact portions 130 a forming double circles on a main body130b. The substrate holding portion 160 has the same arrangement as thatof the substrate holding portion 130. With the substrate holdingportions 130 and 160 as well, the jet medium pressure can be preventedfrom excessively increasing inside the bonded substrate stack 101, sothe bonded substrate stack 101 can be prevented from breaking.

[Fifth Example of Substrate Holding Portion]

FIGS. 16 and 17 are views showing the arrangement of substrate holdingportions according to the fifth example of the present invention. FIG.16 is a perspective view, and FIG. 17 is a front view. Substrate holdingportions 131 and 161 shown in FIGS. 16 and 17 are examples of thesubstrate holding portions 120 and 150 shown in FIG. 2, respectively.

The substrate holding portions 131 and 161 of this modification has aplurality of columnar contact portions 131 a and 161 a on main bodies131 b and 161 b, respectively. With the substrate holding portions 131and 161, the bonded substrate stack 101 can deflect and corrugate having“nodes” at a portion sandwiched by the contact portions 131 a and 161 a,so the separation force can efficiently act inside the bonded substratestack 101. In addition, since the jet medium discharge path is ensured,the jet medium pressure can be prevented from excessively increasinginside the bonded substrate stack 101. As a consequence, the bondedsubstrate stack 101 can be prevented from breaking because of a portionof the porous layer, where the mechanical strength is locally high andseparation progresses slowly.

With the use of the substrate holding portions 131 and 161, the bondedsubstrate stack 101 is completely separated in about 2 min after thestart of jet injection into the bonded substrate stack 101 (separationprocessing).

[Sixth Example of Substrate Holding Portion]

FIGS. 18 and 19 are views showing the arrangement of substrate holdingportions according to the sixth example of the present invention. FIG.18 is a perspective view, and FIG. 19 is a front view. Substrate holdingportions 132 and 162 shown in FIGS. 18 and 19 are examples of thesubstrate holding portions 120 and 150 shown in FIG. 2, respectively.

The substrate holding portions 132 and 162 of this example havecross-shaped (radial) contact portions 132 a and 162 a which come intocontact with the bonded substrate stack 101, on main bodies 132 b and162 b, respectively. With the substrate holding portions 132 and 162,the bonded substrate stack 101 can deflect and corrugate forming “nodes”at a portion sandwiched by the contact portions 132 a and 162 a, so theseparation force efficiently acts on the bonded substrate stack 101. Inaddition, since the jet medium discharge path is ensured, the jet mediumpressure can be prevented from excessively increasing inside the bondedsubstrate stack 101. Therefore, the bonded substrate stack 101 can beprevented from breaking because of a portion of the porous layer, wherethe mechanical strength is locally high and separation progressesslowly.

With the use of the substrate holding portions 132 and 162, the bondedsubstrate stack 101 is completely separated in about 80 sec after thestart of jet injection into the bonded substrate stack 101 (separationprocessing).

FIGS. 20 to 24 are perspective views showing modifications of thesubstrate holding portions shown in FIG. 19. These substrate holdingportions are examples of the substrate holding portions 120 and 150shown in FIG. 2.

Substrate holding portions 133 and 163 shown in FIG. 20 have star-shapedcontact portions 133 a and 163 a which come into contact with the bondedsubstrate stack 101, on main bodies 133 b and 163 b, respectively.Substrate holding portions 134 and 164 shown in FIG. 21 also havestar-shaped contact portions 134 a and 164 a which come into contactwith the bonded substrate stack 101, on main bodies 134 b and 164 b,respectively. Substrate holding portions 135 and 165 shown in FIG. 22have, on main bodies 135 b and 165 b, contact portions 135 a and 165 awhich come into contact with the bonded substrate stack 101,respectively. Each of the contact portions 135 a and 165 a is separatedinto four parts at its central portion and form a cross. A substrateholding portion 136 shown in FIG. 23 has columnar contact portions 136 awhich come into contact with the bonded substrate stack 101, on a mainbody 136 b. A substrate holding portion 166 has the same arrangement asthat of the substrate holding portion 136. Substrate holding portions137 and 167 shown in FIG. 24 have radial contact portions 137 a and 167a which come into contact with the bonded substrate stack 101, on mainbodies 137 b and 167 b, respectively.

[Seventh Example of Substrate Holding Portion]

FIGS. 25 and 26 are sectional views showing the arrangement of substrateholding portions according to the seventh example of the presentinvention. FIG. 25 shows a state before the bonded substrate stack 101is separated. FIG. 26 shows a state after the bonded substrate stack 101is separated. Substrate holding portions 138 and 168 shown in FIGS. 25and 26 are examples of the substrate holding portions 120 and 150 shownin FIG. 2, respectively.

The substrate holding portions 138 and 168 of this example have, ascontact portions to the bonded substrate stack 101, contact portions 138a and 168 a which come into contact with the peripheral portions of thebonded substrate stack 101, respectively. With the substrate holdingportions 138 and 168, the bonded substrate stack 101 can deflect whileexpanding at its central portion having “nodes” at a portion sandwichedby the contact portions 138 a and 168 a and “antinodes” near the centralportion of the bonded substrate stack 101, so the separation force canefficiently act on the bonded substrate stack 101.

The substrate holding portions 138 and 168 have, at their centralportions, limit portions 137 b and 167 b for limiting the deflectionamount of the bonded substrate stack 101. Since the deflection amountsof the separated substrates are limited by the limit portions 137 b and167 b, the substrates can be prevented from breaking.

In the first to sixth examples, the surface of the main body of eachsubstrate holding portion can also function as a deflection amount limitportion. In each example, the projection height of the contact portionto the bonded substrate stack is determined in accordance with thediameter and thickness of the bonded substrate stack and the jet mediumpressure.

The above separating apparatus can be used to separate not only asemiconductor substrate such as a bonded substrate stack but alsovarious samples.

According to the preferred embodiment of the present invention, theefficiency of separation processing can be increased while preventingdamages to the sample to be separated.

In addition, according to the preferred embodiment of the presentinvention, a satisfactory substrate can be manufactured.

Second Embodiment

FIG. 28 is a view showing the schematic arrangement of a separatingapparatus according to the second embodiment of the present invention.In a separating apparatus 1000, the separation force is efficientlyapplied to a bonded substrate stack to separate the bonded substratestack using a low-pressure jet. At the same time, the bonded substratestack is supported to prevent the bonded substrate stack from breakingdue to the separation force. More specifically, the separating apparatus1000 supports the bonded substrate stack while allowing it to warp dueto the pressure of the jet medium injected into the bonded substratestack, and also limiting the warp amount.

The separating apparatus 1000 has substrate holding portions 1120 and1150 having vacuum chuck mechanisms. A bonded substrate stack 101 issandwiched by the substrate holding portions 1120 and 1150 and held. Thebonded substrate stack 101 has a porous layer 101 b as an internalfragile structure and is separated into two substrates 101 a and 101 cat the porous layer 101 b by the separating apparatus 1000. In thisseparating apparatus 1000, the bonded substrate stack is set such thatthe substrate 111a is placed on the first substrate (10′) side in FIG.1D or 41D and the substrate 101 c is placed on the second substrate(10″+20) side in FIG. 1D or 41D.

The substrate holding portions 1120 and 1150 are present on the samerotary axis. The substrate holding portion 1120 is coupled to one end ofa rotary shaft 104 which is rotatably axially supported by a supportbase 109 through a bearing 108. The other end of the rotary shaft 104 iscoupled to the rotary shaft of a motor 110. The rotational forcegenerated by the motor 110 rotates the bonded substrate stack 101vacuum-chucked by the substrate holding portion 1120. In separating thebonded substrate stack 101, the motor 110 rotates the rotary shaft 104at a designated rotation speed in accordance with an instruction from acontroller (not shown).

The substrate holding portion 1150 is coupled to one end of a rotaryshaft 103 which is rotatably and slidably axially supported by thesupport base 109 through a bearing 111. The other end of the rotaryshaft 103 is coupled to an air cylinder 112 fixed on the support base109. When the air cylinder 112 pushes the rotary shaft 103, the bondedsubstrate stack 101 is pressed by the substrate holding portion 1150.

The substrate holding portions 1120 and 1150 can be detached from therotary shafts 104 and 103, respectively. The substrate holding portions1120 and 1150 have one or a plurality of suction portions (e.g., annulargrooves) 1181 and 1182 as vacuum chuck mechanisms, respectively. Thesuction portions 1181 and 1182 communicate with rotary seal portions 104a and 103 a through the rotary shafts 104 and 103, respectively. Therotary seal portions 104 a and 103 a are coupled to vacuum lines 104 band 103 b, respectively. These vacuum lines 104 b and 103 b havesolenoid valves. By controlling the solenoid valves, setting/removal ofthe bonded substrate stack 101 can be controlled.

The substrate holding portions 1120 and 1150 hold the bonded substratestack 101 such that the separation force efficiently acts on the bondedsubstrate stack 101 in separation processing. Specific arrangements ofthe substrate holding portions 1120 and 1150 will be described later.

Substrate separation processing using this separating apparatus 1000will be described below.

To set the bonded substrate stack 101 in the separating apparatus 1000,first, the rotary shaft 103 is retracted by the air cylinder 112 to seta predetermined interval between the chucking surfaces of the substrateholding portions 1120 and 1150. After the bonded substrate stack 101 ismounted on an alignment shaft 113, the air cylinder 112 pushes therotary shaft 103, so the bonded substrate stack 101 is pressed and held(the state shown in FIG. 28). The alignment shaft 113 is rotatablyaxially supported by the support base 109 through bearings 105 and 107.

In this embodiment, the bonded substrate stack 101 is held not by vacuumchucking but by the pressing force of the air cylinder 112. The pressingforce is preferably about 100 to 2000 gf. The bonded substrate stack 101may be vacuum-chucked, as a matter of course. In separation processing,the air cylinder 112 is preferably controlled to maintain apredetermined interval between the substrate holding portions 1120 and1150.

A jet medium (e.g., water) is sent from a pump 114 to a nozzle 102, andprocessing waits until the jet ejected from the nozzle 102 stabilizes.When the jet stabilizes, a shutter 106 is opened to inject the jet intothe separation region of the bonded substrate stack 101. At this time,the bonded substrate stack 101 is rotated by the motor 110. The rotaryshaft 104, substrate holding portion 1120, bonded substrate stack 101,substrate holding portion 1150, and rotary shaft 103 integrally rotate.

When the jet is injected, a separation force due to the pressure of thejet medium continuously injected into the porous layer 101 b as afragile structure acts on the bonded substrate stack 101 to break theporous layer 101 b which connects the substrates 101 a and 101 c. Withthis processing, the bonded substrate stack 101 is separated into twosubstrates in about 2 min.

When the bonded substrate stack 101 is separated into two substrates,the shutter 106 is closed, and the operation of pump 114 is stopped. Bystopping rotation of the motor 110 and controlling the above-describedelectromagnetic valves, the separated substrates are vacuum-chucked bythe substrate holding portions 1120 and 1150.

When the air cylinder 112 retracts the rotary shaft 103, the surfacetension of the jet medium (e.g., water) is cut off to split the twophysically separated substrates to both sides.

When the separation force is to efficiently act on the bonded substratestack 101 while preventing the bonded substrate stack 101 from breaking,the structure of the substrate holding portions 1120 and 1150 must beoptimized. In this embodiment, the separation force is efficientlyapplied by ensuring a space in which the bonded substrate stack warps inseparation processing, and simultaneously, the warp amount is limited toprevent the bonded substrate stack 101 from breaking.

Preferable arrangements of the substrate holding portions will be listedbelow. In the following examples, a pair of substrate holding portionsthat oppose each other have a symmetrical structure. However, thesubstrate holding portions may have independent structures.

[First Example of Substrate Holding Portion]

FIGS. 29 to 31 are views showing the arrangement of the substrateholding portions 1120 and 1150 according to the first example of thesecond embodiment of the present invention. FIG. 29 is a perspectiveview, FIG. 30 is a sectional view showing a state before separationprocessing, and FIG. 31 is a sectional view showing a state duringseparation processing.

The substrate holding portions 1120 and 1150 of this example have convexsupport surfaces 1120 a and 1150 a each formed from part of a sphericalsurface. The support surfaces 1120 a and 1150 a support the bondedsubstrate stack 101 while allowing it to warp and also limit excessivewarp of the bonded substrate stack 101 in separation processing. A warpamount h is preferably set to be around 0.1 to 0.5 mm.

With the use of the separating apparatus 1000 having the substrateholding portions 1120 and 1150, separation progress from the sidesurface of the bonded substrate stack 101 to the vicinity of the centerof the support surfaces 1120 a and 1150 a in about 30 sec after thestart of jet injection into the bonded substrate stack 101 (separationprocessing). Two portions separated from the bonded substrate stack 101are pressed against the support surfaces 1120 a and 1150 a by thepressure (separation force) of the jet medium injected into the bondedsubstrate stack 101, as shown in FIG. 31. As separation processingfurther progresses, the bonded substrate stack 101 is completelyseparated in about 2 min after the start of separation processing.

When the bonded substrate stack 101 is held as it is capable of warping,the separation force can be efficiently applied, so separationprocessing can be efficiently performed. In addition, when the warpamount of the bonded substrate stack 101 is limited, the separatedsubstrates can be prevented from excessively warping, and the bondedsubstrate stack 101 can be prevented from breaking.

To distribute stress acting on the bonded substrate stack 101, thesupport surfaces 1120 a and 1150 a are preferably spherical. However,the contact surfaces need not always be spherical. As a modification ofthe substrate holding portions 1120 and 1150 of the first example,substrate holding portions each having a smooth convex surface will bedescribed.

FIGS. 32 to 35 are sectional views showing modifications of thesubstrate holding portions 1120 and 1150. Substrate holding portions1121 and 1151 shown in FIG. 32 have support surfaces 1121 a and 1151 aeach made of a cone having a convex vertex. Substrate holding portions1122 and 1152 shown in FIG. 33 have support surfaces 1122 a and 1152 aeach made of a frustum of a cone. Substrate holding portions 1123 and1153 shown in FIG. 34 have support surfaces 1123 a and 1153 a each madeof several frustums forming a convex surface as a whole. Substrateholding portions 1124 and 1154 shown in FIG. 35 have support surfaces1124 a and 1154 a each made of several columns forming a convex surfaceas a whole.

As shown in FIGS. 29 to 35, the substrate holding portion preferably hasa diameter with which it can support the entire surface of the bondedsubstrate stack 101. When the diameter of the substrate holding portionis {fraction (2/1)} that of the bonded substrate stack 101 or more, asatisfactory effect can be obtained. However, the present invention doesnot exclude a substrate holding portion having a diameter smaller than ½that of the bonded substrate stack.

The substrate holding portion preferably has a disk shape. However, anyother shape such as a radial or matrix shape may be used.

[Second Example of Substrate Holding Portion]

FIGS. 36 and 37 are sectional views showing the arrangement of substrateholding portions according to the second example of the secondembodiment of the present invention. FIG. 36 shows a state beforeseparation processing. FIG. 37 shows a state during separationprocessing. Substrate holding portions 1125 and 1155 shown in FIGS. 36and 37 replace the substrate holding portions 1120 and 1150 shown inFIG. 28, respectively.

In the substrate holding portions 1125 and 1155 of this example,disk-like support portions 1125 b and 1155 b of an elastic material(e.g., a rubber) are bonded to disk-like main bodies 1125 a and 1155 a,respectively. The support portions 1125 b and 1155 b support the bondedsubstrate stack 101 while allowing it to warp and also limit excessivewarp of the bonded substrate stack 101 in separation processing. Thewarp amount h is preferably set to be around 0.1 to 0.5 mm.

With the use of the separating apparatus 1000 having the substrateholding portions 1125 and 1155, separation progress from the sidesurface of the bonded substrate stack 101 to the vicinity of the centralportion in about 30 sec after the start of jet injection into the bondedsubstrate stack 101 (separation processing). Two portions separated fromthe bonded substrate stack 101 open to form a V shape due to thepressure (separation force) of the jet medium injected into the bondedsubstrate stack 101, as shown in FIG. 37. At this time, the separationforce and the drag of the support portions 1125 b and 1155 b balancewith the warp amount of the bonded substrate stack 101. As separationprocessing further progresses, the bonded substrate stack 101 iscompletely separated in about 2 in after the start of separationprocessing.

When the bonded substrate stack 101 is held as it is capable of warping,the separation force can be efficiently applied, so separationprocessing can be efficiently performed. In addition, when the warpamount of the bonded substrate stack 101 is limited, the separatedsubstrates can be prevented from excessively warping, and the bondedsubstrate stack 101 can be prevented from breaking.

To distribute stress acting on the bonded substrate stack 101, theentire surfaces of the support portions 1125 b and 1155 b are preferablyformed from an elastic material. However, the entire surfaces of thesupport portions need not always be made of an elastic material. Inaddition, the substrate holding portion preferably has a diameter withwhich it can support the entire surface of the bonded substrate stack101. When the diameter of the substrate holding portion is {fraction(2/1)} that of the bonded substrate stack 101 or more, a satisfactoryeffect can be obtained. Modifications of the substrate holding portions1125 and 1155 of this example will be listed below.

FIGS. 38 to 40 are sectional views showing modifications of thesubstrate holding portions 1125 and 1155. In substrate holding portions1126 and 1156 shown in FIG. 38, annular second support portions 1126 band 1156 b each consisting of an elastic material (e.g., a rubber) arefitted on disk-like first support portions 1126 a and 1156 a each havinga convex section. In substrate holding portions 1127 and 1157 shown inFIG. 39, O-ring-like second support portions 1127 b and 1157 b eachconsisting of an elastic material (e.g., a rubber) are fitted ondisk-like first support portions 1127 a and 1157 a each having a convexsection. In substrate holding portions 1128 and 1158 shown in FIG. 40,coil springs 1128 b and 1158 b each having one end coupled to acorresponding one of main bodies 1128 a and 1158 a are fitted on themain bodies 1128 a and 1158 a each having a convex section, and annularsupport portions 1128 c and 1158 c each coupled to the other end of acorresponding one of the coil springs 1128 b and 1158 b are also fittedon the main bodies 1128 a and 1158 a.

The above separating apparatus can be used to separate not only asemiconductor substrate such as a bonded substrate stack but alsovarious samples.

According to the preferred embodiment of the present invention, theefficiency of separation processing can be increased while preventingdamages to the sample to be separated.

In addition, according to the preferred embodiment of the presentinvention, a satisfactory substrate can be manufactured.

Third Embodiment

When this separating apparatus is to be applied to manufacture asemiconductor substrate such as the above-described SOI substrate, purewater or ultrapure water with minimum impurity metals or particles ispreferably used as a jet medium. However, if the substrate is to becleaned after separation, water having low purity may be used as a jetmedium.

The jet medium is not limited to water. It is possible to use an organicsolvent such as an alcohol, an acid such as fluoric acid or nitric acid,an alkali such as potassium hydroxide, a gas such as air, nitrogen gas,carbonic acid gas, rare gas, or an etching gas, or a plasma.

In this separating apparatus, a jet is ejected to the porous layer(separation region) exposed to the side surface of the bonded substratestack, thereby removing the porous layer from the peripheral portion tothe central portion. With this process, the bonded substrate stack isseparated into two substrates by removing only the separation regionwith low mechanical strength without damaging the main body. Even whenthe side surface of the bonded substrate stack is covered with some thinlayer, and the porous layer is not exposed, the thin layer can beremoved by the jet, so the bonded substrate stack can be separated bythe above-described method.

At the outer peripheral portion of the bonded substrate stack, aV-shaped (concave) groove is preferably formed along the side surface.FIGS. 27A and 27B are views showing a force acting on the bondedsubstrate stack. FIG. 27A shows a bonded substrate stack having aV-shaped groove 22. FIG. 27B shows a bonded substrate stack having noV-shaped groove.

As shown in FIG. 27A, in the bonded substrate stack having the V-shapedgroove 22, a force (to be referred to as a separation force hereinafter)is applied outward from the center of the bonded substrate stack, asindicated by an arrow 23. On the other hand, as shown in FIG. 27B, inthe bonded substrate stack with a convex side surface, a force isapplied inward from the side surface of the bonded substrate stack, asindicated by an arrow 24. In the bonded substrate stack having a convexside surface, the separation force does not act unless the side surfaceof a porous layer 12 as the separation region is removed by a jet 21.

Even when a thin film is formed on the side surface of the bondedsubstrate stack, the separation force acts on the bonded substrate stackas far as the bonded substrate stack has the V-shaped groove 22, asshown in FIG. 27A, so the thin layer can be easily broken.

To effectively use the jet, a width W1 of the shaped groove 22 ispreferably equal to or larger than a diameter d of the jet 21. Forexample, assume that each of a first substrate (10) and a secondsubstrate (20) has a thickness of about 1 mm, and the bonded substratestack has a thickness of about 2 mm. Since the width W1 of the V-shapedgroove 22 is normally around 1 mm, the diameter of the jet is preferably1 mm or less.

Since a general water jet apparatus uses a jet with a diameter around0.1 to 0.5 mm, such a general water jet apparatus (e.g., a water jetnozzle) can be used.

The nozzle for ejecting a jet can have not only a circular shape but anyother shapes. For example, when a slit-like nozzle is employed to ejecta jet having a long rectangular section, the jet can be efficientlyinjected into the separation region (inserted between the twosubstrates).

The jet ejection conditions are determined in accordance with the typeof separation region (e.g., a porous layer) or the shape of the sidesurface of the bonded substrate stack. Important parameters as the jetejection conditions are the pressure applied to the jet medium, the jetscanning speed, the width or diameter of the nozzle (the nozzle diameteris almost the same as the jet diameter), the nozzle shape, the distancebetween the nozzle and the separation region, and the flow rate of thejet medium.

The following techniques are used to separate the bonded substratestack. 1) The jet is injected into the bonding interface parallel to thebonding interface while the nozzle is scanned along the bondinginterface. 2) The jet is injected into the bonding interface parallel tothe bonding interface while the bonded substrate stack is scanned. 3)The jet is injected into the bonding interface parallel to the bondinginterface and simultaneously scanned in a fan shape at a pivot near thenozzle. 4) The jet is injected into the bonding interface parallel tothe bonding interface while the bonded substrate stack is rotated aboutnearly the center of the bonded substrate stack (this technique isparticularly effective when the bonded substrate stack has a diskshape). The jet need not always be ejected to be perfectly parallel tothe bonding interface.

The bonded substrate stack is separated not only when the pore wallsbreak by the cutting force, i.e., the impact force of the jet collidingagainst the pore walls in the porous layer but also when the pore wallsbreak by the pressure of jet medium injected into the porous layer. Toprevent damages to the substrate, the separation force acting in theaxial direction of the bonded substrate stack is preferably set to beseveral hundred gf/cm².

To separate the bonded substrate stack using only the cutting force ofjet, the jet must be ejected at a high pressure of 1,000 kg/cm² or more.If the bonded substrate stack is separated by such a high-pressure jet,the substrate may be damaged. The thickness of the bonded substratestack is preferably about 0.5 to 1.0 mm. However, when such a thinbonded substrate stack is to be separated by a high-pressure jet, andthe porous layer locally has portions with high strength, the jetpressure (separation force) may abruptly increase to break the substratebecause the discharge path of the jet medium is not ensured.

Preferably, a jet with a low pressure of approximately 500 kgf/cm² isused, and the shortage of cutting force is compensated for by theseparation force. With this method, damages to the substrate can beprevented at a relatively high ratio.

However, to prevent damages to the substrate, the shape orcharacteristics of the member to be separated is preferably taken intoconsideration. For example, when the bonded substrate stack is to beseparated to the first substrate (10′) side and the second substrate(10″+20) side, the bonded substrate stack holding method in separationprocessing is preferably optimized in consideration of the shape orcharacteristics (especially, the strength) of the substrates. Morespecifically, the first substrate (10) is formed through variousprocesses (including high-temperature process) such as anodizing,formation of an epitaxial layer, and oxidation and therefore readilybreaks as compared to the second substrate (20). If the substrate isused again as the first substrate (10) by removing the porous layerremaining on the surface of the first substrate after separation, thefirst substrate becomes thinner by about 30 μm every time an SOIsubstrate is manufactured. For this reason, as the number of times ofreuse increases, the first substrate breaks during separation processingwith higher probability.

In this embodiment, a separating apparatus is disclosed, in which thedeflection amount by the separation force of the jet is made small forone of members to be separated, which has low strength and readilybreaks, to prevent the member from breaking, and the deflection amountby the separation force of the jet is made large for a member which hashigh strength and hardly breaks to increase the efficiency ofdischarging the jet medium from the separation region (inside themember).

[Arrangement of Separating Apparatus]

A specific arrangement of the separating apparatus according to thethird embodiment of the present invention will be described below withreference to FIGS. 42 to 44.

The separating apparatus of this embodiment is suitable to separate abonded substrate stack having a porous layer or microcavity layer as aninternal fragile structure. This separating apparatus can also be usedto separate another member having an internal fragile structure. In thiscase, the building elements of the separating apparatus must obviouslybe appropriately modified in accordance with the shape of the member tobe separated.

FIG. 42 is a view schematically showing the arrangement of theseparating apparatus according to the third embodiment of the presentinvention. FIG. 43 is a perspective view showing part of the separatingapparatus shown in FIG. 42. FIG. 44 is a view schematically showingseparation processing.

A separating apparatus 2000 has substrate holding portions 2120 and 2130having vacuum chuck mechanisms. A bonded substrate stack 101 issandwiched by the substrate holding portions 2120 and 2130 and held. Thesubstrate holding portion 2120 comes into contact with the bondedsubstrate stack 101 in a large area. The substrate holding portion 2130comes into contact with the bonded substrate stack 101 in a small area.With this structure, the deflection amount becomes small or nodeflection occurs on one side of the bonded substrate stack 101 whilethe deflection amount in separation processing is made relatively largeon the other side.

The bonded substrate stack 101 has a porous layer 101 b as an internalfragile structure and is separated into a first substrate 101 a and asecond substrate 10 c at the porous layer 101 b by the separatingapparatus 2000. The first substrate 101 a corresponds to theabove-described first substrate (10′), and the second substrate 101 ccorresponds to the above-described second substrate (10″+20).

As described above, the first substrate 101 a is formed through variousprocesses (including high-temperature process) such as anodizing,formation of an epitaxial layer, and oxidation and therefore readilybreaks as compared to the second substrate 10 c. Therefore, when thefirst substrate 101 a of the bonded substrate stack 101 is held by thesubstrate holding portion 2120 having a large-area holding surface,deflection of the first substrate 101 a can be limited during separationprocessing and prevented from breaking. The second substrate 101 c has astrength higher than that of the first substrate 101 a and can withstandrelatively large deflection. When the second substrate 101 c is held bythe substrate holding portion 2130 having a small-area holding surface,the substrate 101 c can deflect to some extent in separation processing.With this structure, the jet medium injected between the substrates 101a and 101 c can be efficiently discharged, and consequently, separationprocessing can be efficiently performed.

The substrate holding portion 2120 is coupled to one end of a rotaryshaft 104 which is rotatably axially supported by a support base 109through a bearing 108. The other end of the rotary shaft 104 is coupledto the rotary shaft of a motor 110. The rotational force generated bythe motor 110 rotates the bonded substrate stack 101. The motor 110rotates the rotary shaft 104 at a designated rotation speed inaccordance with an instruction from a controller (not shown).

The substrate holding portion 2130 is coupled to one end of a rotaryshaft 103 which is rotatably and slidably axially supported by thesupport base 109 through a bearing 111. The other end of the rotaryshaft 103 is coupled to an air cylinder 112 fixed on the support base109. When the air cylinder 112 pushes the rotary shaft 103, the bondedsubstrate stack 101 is pressed by the substrate holding portion 2130.

To limit the deflection amount of the first substrate 101 a to an amountas small as possible, the diameter of the chucking surface of thesubstrate holding portion 2120 is preferably made equal to or largerthan the diameter of the bonded substrate stack 101, and additionally,the chucking surface is preferably made flat to support the entiresurface of the first substrate 101 a. However, the shape of the chuckingsurface of the substrate holding portion 2120 is not limited to this.The chucking surface may be a curved surface such as a spherical surfaceor have a smaller area than the bonded substrate stack 101. That is, theshape of the chucking surface of the substrate holding portion 2120 isdetermined in accordance with the allowable deflection amount of thefirst substrate 101 a.

On the other hand, the shape of the chucking surface of the substrateholding portion 2130 is determined within the allowable deflectionamount range of the second substrate 101 c such that the deflectionamount of the second substrate 101 c becomes larger than that of thefirst substrate 101 a.

The substrate holding portions 2120 and 2130 are present on the samerotary axis. The substrate holding portions 2120 and 2139 can bedetached from the rotary shafts 104 and 103, respectively. The substrateholding portions 2120 and 2130 have vacuum chucking grooves on theirholding surfaces, These grooves communicate with vacuum lines extendingthrough the rotary shafts 104 and 103, respectively. These vacuum linesare coupled to external vacuum lines through, e.g., rotary vacuumjoints. The external vacuum lines have solenoid valves. By controllingthe solenoid valves, setting/removal of the substrate stack can becontrolled.

Substrate separation processing using this separating apparatus 2000will be described below.

To set the bonded substrate stack 101 in the separating apparatus 2000,first, the rotary shaft 103 is retracted by the air cylinder 112 to seta predetermined interval between the holding surfaces of the substrateholding portions 2120 and 2130. After the bonded substrate stack 101 ismounted on an alignment shaft 113, the air cylinder 112 pushes therotary shaft 103, so the bonded substrate stack 101 is pressed and held(the state shown in FIG. 42). The alignment shaft 113 is rotatablyaxially supported through bearings 105 and 107.

In this embodiment, the bonded substrate stack 101 is held not by vacuumchucking but by the pressing force of the air cylinder 112. The pressingforce is preferably about 100 to 2000 gf. The bonded substrate stack 101may be vacuum-chucked, as a matter of course.

A jet medium (e.g., water) is sent from a pump 114 to a jet nozzle 102,and processing waits until the jet ejected from the jet nozzle 102stabilizes. When the jet stabilizes, a shutter 106 is opened to injectthe jet into the separation region of the bonded substrate stack 101,and at the same time, the bonded substrate stack 101 is rotated by themotor 110. At this time, the rotary shaft 104, substrate holding portion2120, bonded substrate stack 101, substrate holding portion 2130, androtary shaft 103 integrally rotate. The jet nozzle 102 is attached to aposition adjustment mechanism (e.g., an X-Y stage), so the position fromwhich the jet is injected into the bonded substrate stack 101 can beadjusted by the position adjustment mechanism.

When the jet is injected, a separation force due to the pressure of jetmedium continuously injected into the porous layer 101 b as a fragilestructure acts on the bonded substrate stack 101 to break the porouslayer 101 b which connects the substrates 101 a and 101 c. At this time,the substrates 101 a and 101 c deflect in the allowable ranges of thesubstrate holding portions 2120 and 2130. In this separating apparatus2000, the deflection amount of the substrate 101 a is relatively small,and that of the substrate 101 c is relatively large.

With this processing, the bonded substrate stack 101 is separated intotwo substrates in about 2 min.

When the bonded substrate stack 101 is separated into two substrates,the shutter 106 is closed, and the operation of pump 114 is stopped. Bystopping rotation of the motor 110 and controlling the above-describedelectromagnetic valves, the separated substrates 101 a and 110 c arevacuum-chucked by the substrate holding portions 2120 and 2130.

When the air cylinder 112 retracts the rotary shaft 103, the surfacetension of the jet medium (e.g., water) is cut off to split the twophysically separated substrates 101 a and 101 c to both sides.

Modifications of the substrate holding portion of the separatingapparatus 2000 will be described next.

[First Modification]

In the separating apparatus of this modification, the substrate holdingportions 2120 and 2130 of the separating apparatus 2000 shown in FIGS.42 to 44 are replaced with each other. FIG. 45 is a view showing theschematic arrangement of a separating apparatus 2000′ of thismodification.

In this separating apparatus 2000′, the substrate holding portion 2120holds the first substrate 101 a side of the bonded substrate stack 101,and the substrate holding portion 2130 holds the second substrate 101 c.That is, in the separating apparatus 2000′, the bonded substrate stack101 is held such that the second substrate 101 c is positioned on theside of the rotary shaft 104 whose horizontal position is fixed.

This separating apparatus 2000′ is suitable to reuse the first substrate101 a after separation as the first substrate (10) by removing theporous layer 101 b remaining on the surface of the substrate 101 a. Thereason for this is as follows.

When the first substrate 101 a is to be reused, the first substrate 101a becomes thinner in accordance with the number of times of reuse. Forthis reason, when separation processing is to be efficiently andappropriately performed in the separating apparatus 2000 shown in FIG.42, the jet nozzle 102 must be located immediately above the separationregion of the bonded substrate stack 101 for every separationprocessing. If the position of the jet nozzle 102 is fixed, the jet maynot be injected into the center of the porous layer 101 b to damage thesubstrates 101 a and 10 c.

However, in the separating apparatus 2000′ of this modification, as faras the bonded substrate stack 101 whose second substrate 101 c has apredetermined thickness is to be processed, the positional relationshipbetween the porous layer 101 b and the jet nozzle 102 does not changeeven when the position of the jet nozzle 102 is fixed. This is becausethe position of the substrate holding portion 2130 is fixed, and thesecond substrate 101 c held by the substrate holding portion 2130 has apredetermined thickness.

[Second Modification]

In this modification, the structure of each substrate holding portion ofthe separating apparatus 2000 shown in FIGS. 42 to 44 is modified. FIG.46 is a view showing the schematic arrangement of the substrate holdingportions of the separating apparatus of this modification. In thisseparating apparatus, a substrate holding portion 2121 having an almostcircular chucking surface holds the first substrate 101 a side of thebonded substrate stack 101, and a substrate holding portion 2131 havingan almost annular chucking surface holds the second substrate 101 c sideof the bonded substrate stack 101.

The substrate holding portions 2121 and 2131 of this modification limitthe deflection amounts of the first substrate 101 a and that of thesecond substrate 101 c in the allowable deflection amount ranges,respectively, and increase the efficiency of separation processing whilepreventing damages to the substrates 101 a and 101 c.

Since the diameter of the substrate holding portion 2121 is smaller thanthe bonded substrate stack 101, the first substrate 101 a deflects whilewarping at its outer peripheral portion in separation processing. Theholding surface of the substrate holding portion 2121 may be a flatsurface or a curved surface such as a spherical surface. On the otherhand, since the substrate holding portion 2131 has an annular holdingsurface, the substrate 101 c deflects while corrugating forming “nodes”near the chucking surface (701 and 702 in FIG. 46) and “antinodes” atthe outer peripheral portion and central portion. When the substrateholding portions 2121 and 2131 with shapes allowing the second substrate101 c to deflect while corrugating are employed, the jet medium injectedinto the bonded substrate stack 101 can be efficiently discharged.

Separation processing was executed using this separating apparatus.After the jet was injected into the bonded substrate stack 101, the jetproceeded to the holding surface (701 in FIG. 46) of the substrateholding portion 2131 in about 30 sec. After this, the jet proceeded tothe holding surface (702 in FIG. 46) on the opposite side after about 30sec, and the substrate 101 c deflected while corrugating, as shown inFIG. 46. The bonded substrate stack 101 was separated into twosubstrates in about 3 min.

In separation processing of the bonded substrate stack 101, the jetmedium is hardly discharged at the central portion of bonded substratestack. For this reason, the pressure of the jet medium readilyincreases, so the central portion is easily damaged as compared to theperipheral portion. Hence, when only the second substrate 101 c withhigh strength is allowed to deflect while expanding to the substrateholding portion 2131 side at its central portion, as in the substrateholding portions of this modification, the discharge path of the jetmedium can be ensured while preventing damages to the first substrate101 a with low strength.

[Third Modification]

In this modification, the structures of the substrate holding portions2120 and 2130 of the separating apparatus 2000 shown in FIGS. 42 to 44are modified. FIG. 47 is a view showing a modification of the substrateholding portion 2120 for holding the first substrate side. FIG. 48 is aview showing a modification of the substrate holding portion 2130 forholding the second substrate side.

As shown in FIG. 47, a substrate holding portion 2122 for holding thefirst substrate 101 a side has a diameter slightly smaller than that ofthe bonded substrate stack 101 and a flat chucking surface. Therefore,the first substrate 101 a deflects while warping at its outer peripheralportion in separation processing.

On the other hand, as shown in FIG. 48, a substrate holding portion 2132has a plurality of projecting chuck portions 2132 a. The secondsubstrate 101 c side of the bonded substrate stack 101 is held by thetips of the plurality of chuck portions 2132 a. When the secondsubstrate 101 c side is held by the projecting suction portions 2132 a,the substrate 101 c can easily deflect, and the jet medium injected intothe bonded substrate stack 101 can be efficiently discharged. To stablyhold the bonded substrate stack 101, the number of projecting chuckportions 2132 a is preferably three or more.

The present invention is not limited to the above embodiments andvarious changes and modifications can be made within the spirit andscope of the present invention. Therefore, to apprise the public of thescope of the present invention, the following claims are made.

What is claimed is:
 1. A separating apparatus for separating aplate-like sample having an internal fragile layer at the fragile layercomprising: a jet unit for ejecting a fluid to the sample; and a pair ofholding portions opposing each other to sandwich and hold the sample,wherein said pair of holding portions allow the sample to warp as thesample is divided into two parts by a pressure of the fluid ejected fromsaid jet unit and injected into the sample and simultaneously limit awarp amount.
 2. The apparatus according to claim 1, wherein at least oneof said pair of holding portions has a smooth convex support surface,and the sample is held by said support surface.
 3. The apparatusaccording to claim 2, wherein said support surface substantiallycomprises part of a spherical surface.
 4. The apparatus according toclaim 2, wherein said support surface comprises a surface formed by acone with a convex vertex.
 5. The apparatus according to claim 2,wherein said support surface substantially comprises a surface formed bya frustum of a cone.
 6. The apparatus according to claim 2, wherein saidsupport surface comprises a smooth convex surface formed by a stack ofseveral frustums.
 7. The apparatus according to claim 2, wherein saidsupport surface comprises a convex surface formed by a stack of severalcolumns.
 8. The apparatus according to claim 1, wherein at least one ofsaid pair of holding portions includes an elastic member and deforms dueto a force inflicted by the sample.
 9. The apparatus according to claim1, wherein at least one of said holding portions has a support portionpartially consisting of an elastic material, and the sample is held bysaid support portion.
 10. The apparatus according to claim 1, wherein atleast one of said holding portions has an elastic member at a portionwhich can contact the sample.
 11. The apparatus according to claim 1,wherein at least one of said holding portions has an annular supportportion consisting of an elastic member.
 12. The apparatus according toclaim 1, wherein at least one of said holding portions has a supportportion coupled to a main body via an elastic member.
 13. The apparatusaccording to claim 1, further comprising a rotary mechanism for rotatingsaid holding portion about a shaft perpendicular to a surface of thesample.
 14. The apparatus according to claim 1, further comprising anadjustment mechanism for adjusting an interval between said pair ofholding portions.
 15. The apparatus according to claim 14, wherein inseparating the sample by the fluid, said adjustment mechanism pressesthe sample to adjust the interval between said pair of holding portions.16. The apparatus according to claim 14, wherein in separating thesample by the fluid, said adjustment mechanism maintains a substantiallyconstant interval between said pair of holding portions.
 17. Theapparatus according to claim 1, wherein each of said pair of holdingportions has a chuck mechanism for vacuum-chucking the sample.
 18. Theapparatus according to claim 1, wherein the sample comprises a substratehaving a porous layer as the fragile layer.
 19. A support apparatus forsupporting a sample, which is used in a separating apparatus forseparating a plate-like sample having an internal fragile layer at thefragile layer comprising: a pair of holding portions for sandwiching andholding the sample, wherein said pair of holding portions allow thesample to warp as the sample is divided into two parts by a pressure ofthe fluid ejected from a jet unit arranged in said separating apparatusand injected into the sample and simultaneously limit a warp amount. 20.The apparatus according to claim 19, wherein at least one of said pairof holding portions has a smooth convex support surface, and the sampleis held by said support surface.
 21. The apparatus according to claim20, wherein said support surface substantially comprises part of aspherical surface.
 22. The apparatus according to claim 20, wherein saidsupport surface comprises a surface formed by a cone with a convexvertex.
 23. The apparatus according to claim 20, wherein said supportsurface substantially comprises a surface formed by a frustum of a cone.24. The apparatus according to claim 20, wherein said support surfacecomprises a smooth convex surface formed by a stack of several frustums.25. The apparatus according to claim 20, wherein said support surfacecomprises a convex surface formed by a stack of several columns.
 26. Theapparatus according to claim 19, wherein at least one of said pair ofholding portions includes an elastic member and deforms due to a forceinflicted by the sample.
 27. The apparatus according to claim 19,wherein at least one of said holding portions has a support portionpartially consisting of an elastic material, and the sample is held bysaid support portion.
 28. The apparatus according to claim 19, whereinat least one of said holding portions has an elastic member at a portionwhich can contact the sample.
 29. The apparatus according to claim 19,wherein at least one of said holding portions has an annular supportportion consisting of an elastic member.
 30. The apparatus according toclaim 19, wherein at least one of said holding portions has a supportportion coupled to a main body via an elastic member.
 31. The apparatusaccording to claim 19, further comprising a rotary mechanism forrotating said holding portion about a shaft perpendicular to a surfaceof the sample.
 32. The apparatus according to claim 19, furthercomprising an adjustment mechanism for adjusting an interval betweensaid pair of holding portions.
 33. The apparatus according to claim 32,wherein in separating the sample by the fluid, said adjustment mechanismpresses the sample to adjust the interval between said pair of holdingportions.
 34. The apparatus according to claim 32, wherein in separatingthe sample by the fluid, said adjustment mechanism maintains asubstantially constant interval between said pair of holding portions.35. The apparatus according to claim 19, wherein each of said pair ofholding portions has a chuck mechanism for vacuum-chucking the sample.36. The apparatus according to claim 19, wherein the sample comprises asubstrate having a porous layer as the fragile layer.
 37. A separatingmethod of separating a plate-like sample having an internal fragilelayer at the fragile layer comprising the steps of: transferring thesample to said separating apparatus of claim 1; separating the sample atthe fragile layer by said separating apparatus; and receiving theseparated samples from said separating apparatus.
 38. The methodaccording to claim 37, wherein water is used as the fluid to be ejectedfrom said jet unit.
 39. A separating method of separating a substrate ata porous layer, the substrate being formed by bonding a non-porous layerside of a first substrate, in which the porous layer and the non-porouslayer are sequentially formed on one surface, to a second substrate,wherein said separating apparatus of claim 1 is used for separation. 40.A substrate manufacturing method comprising the step of: bonding anon-porous layer side of a first substrate, in which a porous layer andthe non-porous layer are sequentially formed on one surface, to a secondsubstrate; and separating the bonded substrates at the porous layer,wherein said separating apparatus of claim 1 is used in the separationstep.